Rotary machine having spacers for control of fluid dynamics

ABSTRACT

A system includes a rotary machine with a fluid flow path extending along an axis of the rotary machine, a plurality of airfoils disposed about the axis, and a plurality of spacers disposed about the axis. Each spacer of the plurality of spacers is disposed circumferentially between adjacent airfoils of the plurality of airfoils to define a circumferential spacing of the airfoils about the axis.

BACKGROUND OF THE INVENTION

The subject matter disclosed herein relates to rotary machines and, moreparticularly, turbines and compressors susceptible to resonant behaviorin a fluid flow.

Turbines and compressors exchange energy between a fluid and a rotor.For example, a turbine generates energy in response to a fluid flowacting on a plurality of blades, whereas a compressor uses energy todrive a plurality of blades to compress a gas. Unfortunately, therotation of the blades can create wake and bow waves, which can exciteother rotating and stationary structures upstream and downstream fromthe blades. For example, the wake and bow waves may cause vibration,premature wear, and damage of vanes, blades, nozzles, airfoils, rotors,and other structures in the fluid flow.

BRIEF DESCRIPTION OF THE INVENTION

Certain embodiments commensurate in scope with the originally claimedinvention are summarized below. These embodiments are not intended tolimit the scope of the claimed invention, but rather these embodimentsare intended only to provide a brief summary of possible forms of theinvention. Indeed, the invention may encompass a variety of forms thatmay be similar to or different from the embodiments set forth below.

In a first embodiment, a system includes a rotary machine with a fluidflow path extending along an axis of the rotary machine, a plurality ofairfoils disposed about the axis, and a plurality of spacers disposedabout the axis. Each spacer of the plurality of spacers may be disposedcircumferentially between adjacent airfoils of the plurality of airfoilsto define a circumferential spacing of the airfoils about the axis.

In a second embodiment, a system includes a rotary machine with a fluidflow path and a plurality of segments disposed in an annular arrangementalong the fluid flow path. The plurality of segments include spacersegments and flow control segments. The flow control segments protrudeinto the fluid flow path. Each spacer segment is disposedcircumferentially between adjacent flow control segments to define acircumferential spacing of the flow control segments.

In a third embodiment, a method includes mounting a plurality of airfoilsegments in a rotary machine along a fluid flow path, and spacing theplurality of airfoil segments in a circumferential spacing with aplurality of spacer segments.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIG. 1 is a sectional view of an embodiment of a gas turbine enginesectioned through a longitudinal axis;

FIG. 2 is a front view of an embodiment of a rotor with a non-uniformspacing of blades;

FIG. 3 is a front view of an embodiment of a rotor with a non-uniformspacing of blades;

FIG. 4 is a front view of an embodiment of a rotor with a non-uniformspacing of blades;

FIG. 5 is a perspective view of an embodiment of three rotors, whereineach rotor has a different non-uniform spacing of blades;

FIG. 6 is a partial front view of an embodiment of a rotor withdifferently sized spacers between blades;

FIG. 7 is a top view of an embodiment of a rotor with differently sizedspacers between blades;

FIG. 8 is a top view of an embodiment of a rotor with differently sizedspacers between blades;

FIG. 9 is a front view of an embodiment of a blade having a T-shapedgeometry;

FIG. 10 is a partial front view of an embodiment of a rotor with bladeshaving differently sized bases;

FIG. 11 is a top view of an embodiment of a rotor with blades havingdifferently sized bases;

FIG. 12 is a top view of an embodiment of a rotor with blades havingdifferently sized bases;

FIG. 13 is a partial front view of an embodiment of a stator withdifferently sized spacers between vanes;

FIG. 14 is a partial front view of an embodiment of a stator with vaneshaving differently sized bases;

FIG. 15 is a partial front view of an embodiment of a rotor with uniformlarge spacers between blades;

FIG. 16 is a partial front view of an embodiment of a rotor with uniformmedium spacers between blades;

FIG. 17 is a partial front view of an embodiment of a rotor with uniformsmall spacers between blades;

FIG. 18 is a graph illustrating resonant frequency of stators and rotorswith differently sized spacers with respect to the rotational speed ofthe engine;

FIG. 19 is a partial front view of an embodiment of a stator withuniform large sized spacers between vanes;

FIG. 20 is a partial front view of an embodiment of a stator withuniform medium spacers between vanes; and

FIG. 21 is a partial front view of an embodiment of a stator withuniform small spacers between vanes.

DETAILED DESCRIPTION OF THE INVENTION

One or more specific embodiments of the present invention will bedescribed below. In an effort to provide a concise description of theseembodiments, all features of an actual implementation may not bedescribed in the specification. It should be appreciated that in thedevelopment of any such actual implementation, as in any engineering ordesign project, numerous implementation-specific decisions must be madeto achieve the developers' specific goals, such as compliance withsystem-related and business-related constraints, which may vary from oneimplementation to another. Moreover, it should be appreciated that sucha development effort might be complex and time consuming, but wouldnevertheless be a routine undertaking of design, fabrication, andmanufacture for those of ordinary skill having the benefit of thisdisclosure.

When introducing elements of various embodiments of the presentinvention, the articles “a,” “an,” “the,” and “said” are intended tomean that there are one or more of the elements. The terms “comprising,”“including,” and “having” are intended to be inclusive and mean thatthere may be additional elements other than the listed elements.

The disclosed embodiments are directed toward tuning of fluid dynamicsin rotary machines, such as a turbine or a compressor, via an adjustmentof the spacing between rotating blades or stationary vanes and/or anadjustment of the count of rotating blades or stationary vanes. Inparticular, the disclosed embodiments adjust the spacing and/or count ofblades or vanes to control the frequency of wake and bow waves formed bythe rotating blades, stationary vanes, or other structures in the fluidflow. For example, a non-uniform spacing or modified count of rotatingblades or stationary vanes may reduce the possibility of resonantbehavior, vibration, and undesirable fluid dynamics in the turbine orcompressor. In other words, the non-uniform spacing or modified count ofrotating blades or stationary vanes may reduce or eliminate the abilityof the wake and bow waves to cause resonance in structures along thefluid flow path. Instead, the non-uniform spacing or modified count ofrotating blades or stationary vanes may dampen and reduce the responseof structures in the fluid flow path by changing the frequency of thewake and bow waves. The non-uniform spacing or modified count may beachieved with spacers, modified mounting structures, mounting adapters,modified stators, modified rotors, or some combination thereof.

For example, the non-uniform spacing of the blades or vanes may beachieved with differently sized spacers between adjacent blades orvanes, differently sized bases of adjacent blades or vanes, or anycombination thereof. The non-uniform spacing of the blades or vanes mayinclude both non-uniform spacing of the blades about a circumference ofa particular stage (e.g., turbine or compressor stage), non-uniformspacing of the blades from one stage to another, or a combinationthereof. The non-uniform spacing effectively reduces and dampens thewake and bow waves generated by the rotating blades, thereby reducingthe possibility of vibration, premature wear, and damage caused by suchwake and bow waves on stationary and rotating structures.

By further example, the modified count of blades or vanes may beachieved by uniformly spacing a greater or smaller count of blades orvanes via spacers, modified mounting bases, or a combination thereof. Incertain embodiments employing spacers, a first set of spacers (e.g.,large spacers) may be used to provide a first uniform spacing of bladesor vanes, a second set of spacers (e.g., medium spacers) may be used toprovide a second uniform spacing of blades or vanes, a third set ofspacers (e.g., small spacers) may be used to provide a third uniformspacing of blades or vanes, and so forth. Similarly, in certainembodiments employing modified bases, a first set of blades or vaneswith a first mounting base size (e.g., large mounting base) may be usedto provide a first uniform spacing of blades or vanes, a second set ofblades or vanes with a second mounting base size (e.g., medium mountingbase) may be used to provide a second uniform spacing of blades orvanes, a third set of blades or vanes with a third mounting base size(e.g., small mounting base) may be used to provide a third uniformspacing of blades or vanes, and so forth. In each embodiment, the bladeor vane count may be increased or decreased to change the frequency ofwake and bow waves at specific rotational speeds of the rotary machine.Thus, the modified count is configured to change the frequency of thewake and bow waves to avoid the resonant frequency of the structures inthe fluid flow path at specific rotational speeds.

The disclosed embodiments of non-uniform spacing or modified count ofrotating blades or stationary vanes may be utilized in any suitablerotary machine, such as turbines, compressors, and rotary pumps.However, for purposes of discussion, the disclosed embodiments arepresented in context of a gas turbine engine. FIG. 1 is across-sectional side view of an embodiment of a gas turbine engine 150.As described further below, a non-uniform spacing or modified count ofrotating blades or stationary vanes may be employed within the gasturbine engine 150 to reduce and/or dampen periodic oscillations,vibration, and/or harmonic behavior of wake and bow waves in the fluidflow. For example, a non-uniform spacing or modified count of rotatingblades or stationary vanes may be used in a compressor 152 and a turbine154 of the gas turbine engine 150. Furthermore, the non-uniform spacingor modified count of rotating blades or stationary vanes may be used ina single stage or multiple stages of the compressor 152 and the turbine154, and may vary from one stage to another.

In the illustrated embodiment, the gas turbine engine 150 includes anair intake section 156, the compressor 152, one or more combustors 158,the turbine 154, and an exhaust section 160. The compressor 152 includesa plurality of compressor stages 162 (e.g., 1 to 20 stages), each havinga plurality of rotating compressor blades 164 and stationary compressorvanes 166. The compressor 152 is configured to intake air from the airintake section 156 and progressively increase the air pressure in thestages 162. Eventually, the gas turbine engine 150 directs thecompressed air from the compressor 152 to the one or more combustors158. Each combustor 158 is configured to mix the compressed air withfuel, combust the fuel air mixture, and direct hot combustion gasestoward the turbine 154. Accordingly, each combustor 158 includes one ormore fuel nozzles 168 and a transition piece 170 leading toward theturbine 154. The turbine 154 includes a plurality of turbine stages 172(e.g., 1 to 20 stages), such as stages 174, 176, and 178, each having aplurality of rotating turbine blades 180 and stationary nozzleassemblies or turbine vanes 182. In turn, the turbine blades 180 arecoupled to respective turbine wheels 184, which are coupled to arotating shaft 186. The turbine 154 is configured to intake the hotcombustion gases from the combustors 158, and progressively extractenergy from the hot combustion gases to drive the blades 180 in theturbine stages 172. As the hot combustion gases cause rotation of theturbine blades 180, the shaft 186 rotates to drive the compressor 152and any other suitable load, such as an electrical generator.Eventually, the gas turbine engine 150 diffuses and exhausts thecombustion gases through the exhaust section 160.

As discussed in detail below, a variety of embodiments of non-uniformspacing or modified count of rotating blades or stationary vanes may beused in the compressor 152 and the turbine 154 to tune the fluiddynamics in a manner that reduces undesirable behavior, such asresonance and vibration. For example, as discussed with reference toFIGS. 2-14, a non-uniform spacing of the compressor blades 164, thecompressor vanes 166, the turbine blades 180, and/or the turbine vanes182 may be selected to reduce, dampen, or frequency shift the wake andbow waves created in the gas turbine engine 150. Similarly, as discussedwith reference to FIGS. 15-21, a modified count (e.g., modified uniformspacing) of the compressor blades 164, the compressor vanes 166, theturbine blades 180, and/or the turbine vanes 182 may be selected toreduce, dampen, or frequency shift the wake and bow waves created in thegas turbine engine 150. In these various embodiments, the non-uniformspacing or modified count of rotating blades or stationary vanes isspecifically selected to reduce the possibility of resonance andvibration, thereby improving the performance and increasing thelongevity of the gas turbine engine 150.

FIG. 2 is a front view of an embodiment of a rotor 200 withnon-uniformly spaced blades. In certain embodiments, the rotor 200 maybe disposed in a turbine, a compressor, or another rotary machine. Forexample, the rotor 200 may be disposed in a gas turbine, a steamturbine, a water turbine, or any combination thereof. Furthermore, therotor 200 may be used in multiple stages of a rotary machine, each havethe same or different arrangement of the non-uniformly spaced blades.

The illustrated rotor 200 has non-uniformly spaced blades 208, which maybe described by dividing the rotor 200 into two equal sections 202 and204 (e.g., 180 degrees each) via an intermediate line 206. In certainembodiments, each section 202 and 204 may have a different number ofblades 208, thereby creating non-uniform blade spacing. For example, theillustrated upper section 202 has three blades 208, while theillustrated lower section 204 has six blades 208. Thus, the uppersection 202 has half as many blades 208 as the lower section 204. Inother embodiments, the upper and lower sections 202 and 204 may differin the number of blades 208 by approximately 1 to 1.005, 1 to 1.01, 1 to1.02, 1 to 1.05, or 1 to 3. For example, the percentage of blades 208 ofthe upper section 202 relative to the lower section 204 may rangebetween approximately 50 to 99.99 percent, 75 to 99.99 percent, 95 to99.99, or 97-99.99 percent. However, any difference in the number ofblades 208 between the upper and lower sections 202 and 204 may beemployed to reduce and dampen wake and bow waves associated withrotation of the blades 208 on stationary airfoils or structures.

In addition, the blades 208 may be evenly or unevenly spaced within eachsection 202 and 204. For example, in the illustrated embodiment, theblades 208 in the upper section 202 are evenly spaced from one anotherby a first circumferential spacing 210 (e.g., arc lengths), while theblades 208 in the lower section 204 are evenly spaced from one anotherby a second circumferential spacing 212 (e.g., arc lengths). Althougheach section 202 and 204 has equal spacing, the circumferential spacing210 is different from the circumferential spacing 212. In otherembodiments, the circumferential spacing 210 may vary from one blade 208to another in the upper section 202 and/or the circumferential spacing212 may vary from one blade 208 to another in the lower section 204. Ineach of these embodiments, the non-uniform blade spacing is configuredto reduce the possibility of resonance on stationary airfoils andstructures due to periodic generation of wake and bow waves by rotatingairfoils or structures. The non-uniform blade spacing may effectivelydampen and reduce the wake and bow waves due to their non-periodicgeneration by the non-uniform rotating airfoils or structures. In thismanner, the non-uniform blade spacing is able to lessen the impact ofwake and bow waves on various downstream components, e.g., vanes,nozzles, stators, airfoils, etc.

FIG. 3 is a front view of an embodiment of a rotor 220 withnon-uniformly spaced blades. In certain embodiments, the rotor 220 maybe disposed in a turbine, a compressor, or another rotary machine. Forexample, the rotor 220 may be disposed in a gas turbine, a steamturbine, a water turbine, or any combination thereof. Furthermore, therotor 220 may be used in multiple stages of a rotary machine, each havethe same or different arrangement of the non-uniformly spaced blades.

The illustrated rotor 220 has non-uniformly spaced blades 234, which maybe described by dividing the rotor 220 into four equal sections 222,224, 226, and 228 (e.g., 90 degrees each) via intermediate lines 230 and232. In certain embodiments, at least one or more of the sections 222,224, 226, and 228 may have a different number of blades 234 relative tothe other sections, thereby creating non-uniform blade spacing. Forexample, the sections 222, 224, 226, and 228 may have 1, 2, 3, or 4different numbers of blades 234 in the respective sections. In theillustrated embodiment, each section 222, 224, 226, and 228 has adifferent number of blades 234. Section 222 has 3 blades equally spacedfrom one another by a circumferential distance 236, section 224 has 6blades equally spaced from one another by a circumferential distance238, section 226 has 2 blades equally spaced from one another by acircumferential distance 240, and section 228 has 5 blades equallyspaced from one another by a circumferential distance 242. In thisembodiment, sections 224 and 226 have an even yet different number ofblades 234, while sections 222 and 228 have an odd yet different numberof blades 234. In other embodiments, the sections 222, 224, 226, and 228may have any configuration of even and odd numbers of blades 234,provided that at least one section has a different number of blades 234relative to the remaining sections. For example, the sections 222, 224,226, and 228 may vary in the number of blades 234 with respect to eachother by approximately 1 to 1.005, 1 to 1.01, 1 to 1.02, 1 to 1.05, or 1to 3.

In addition, the blades 234 may be evenly or unevenly spaced within eachsection 222, 224, 226, and 228. For example, in the illustratedembodiment, the blades 234 in the section 222 are evenly spaced from oneanother by the first circumferential spacing 236 (e.g., arc lengths),the blades 234 in the section 224 are evenly spaced from one another bythe second circumferential spacing 238 (e.g., arc lengths), the blades234 in the section 226 are evenly spaced from one another by the thirdcircumferential spacing 240 (e.g., arc lengths), and the blades 234 inthe section 228 are evenly spaced from one another by the fourthcircumferential spacing 242 (e.g., arc lengths). Although each section222, 224, 226, and 228 has equal spacing, the circumferential spacing236, 238, 240, and 242 varies from one section to another. In otherembodiments, the circumferential spacing may vary within each individualsection. In each of these embodiments, the non-uniform blade spacing isconfigured to reduce the possibility of resonance due to periodicgeneration of wake and bow waves. Furthermore, the non-uniform bladespacing may effectively dampen and reduce the response of stationaryairfoils or structures by the rotating airfoils or structure's wake andbow waves due to their non-periodic generation by the blades 234. Inthis manner, the non-uniform blade spacing is able to lessen the impactof wake and bow waves on various downstream components, e.g., vanes,nozzles, stators, airfoils, etc.

FIG. 4 is a front view of an embodiment of a rotor 250 withnon-uniformly spaced blades. In certain embodiments, the rotor 250 maybe disposed in a turbine, a compressor, or another rotary machine. Forexample, the rotor 250 may be disposed in a gas turbine, a steamturbine, a water turbine, or any combination thereof. Furthermore, therotor 250 may be used in multiple stages of a rotary machine, each havethe same or different arrangement of the non-uniformly spaced blades.

The illustrated rotor 250 has non-uniformly spaced blades 264, which maybe described by dividing the rotor 250 into three equal sections 252,254, and 256 (e.g., 120 degrees each) via intermediate lines 258, 260,and 262. In certain embodiments, at least one or more of the sections252, 254, and 256 may have a different number of blades 264 relative tothe other sections, thereby creating non-uniform blade spacing. Forexample, the sections 252, 254, and 256 may have 2 or 3 differentnumbers of blades 264 in the respective sections. In the illustratedembodiment, each section 252, 254, and 256 has a different number ofblades 264. Section 252 has 3 blades equally spaced from one another bya circumferential distance 266, section 254 has 6 blades equally spacedfrom one another by a circumferential distance 268, and section 256 has5 blades equally spaced from one another by a circumferential distance270. In this embodiment, sections 252 and 256 have an odd yet differentnumber of blades 264, while section 254 has an even number of blades264. In other embodiments, the sections 252, 254, and 256 may have anyconfiguration of even and odd numbers of blades 264, provided that atleast one section has a different number of blades 264 relative to theremaining sections. For example, the sections 252, 254, and 256 may varyin the number of blades 264 with respect to each other by approximately1 to 1.005, 1 to 1.01, 1 to 1.02, 1 to 1.05, or 1 to 3.

In addition, the blades 264 may be evenly or unevenly spaced within eachsection 252, 254, and 256. For example, in the illustrated embodiment,the blades 264 in the section 252 are evenly spaced from one another bythe first circumferential spacing 266 (e.g., arc lengths), the blades264 in the section 254 are evenly spaced from one another by the secondcircumferential spacing 268 (e.g., arc lengths), and the blades 264 inthe section 256 are evenly spaced from one another by the thirdcircumferential spacing 270 (e.g., arc lengths). Although each section252, 254, and 256 has equal spacing, the circumferential spacing 266,268, and 270 varies from one section to another. In other embodiments,the circumferential spacing may vary within each individual section. Ineach of these embodiments, the non-uniform blade spacing is configuredto reduce the possibility of resonance due to periodic generation ofwake and bow waves. Furthermore, the non-uniform blade spacing mayeffectively dampen and reduce the response of stationary airfoils orstructures by the rotating airfoils or structure's wake and bow wavesdue to their non-periodic generation by the blades 264. In this manner,the non-uniform blade spacing is able to lessen the impact of wake andbow waves on various downstream components, e.g., vanes, nozzles,stators, airfoils, etc.

FIG. 5 is a perspective view of an embodiment of three rotors 280, 282,and 284, wherein each rotor has a different non-uniform spacing ofblades 286. For example, the illustrated rotors 280, 282, and 284 maycorrespond to three stages of the compressor 152 or the turbine 154 asillustrated in FIG. 1. As illustrated, each of the rotors 280, 282, and284 has non-uniform spacing of blades 286 between respective uppersections 288, 290, and 292 and respective lower sections 294, 296, and298. For example, the rotor 280 includes three blades 286 in the uppersection 288 and five blades 286 in the lower section 294, the rotor 282includes four blades 286 in the upper section 290 and six blades 286 inthe lower section 296, and the rotor 284 includes five blades 286 in theupper section 292 and seven blades 286 in the lower section 298. Thus,the upper sections 280, 282, and 284 have a greater number of blades 286relative to the lower sections 294, 296, and 298 in each respectiverotor 280, 282, and 284. In the illustrated embodiment, the number ofblades 286 increases by one blade 286 from one upper section to another,while also increasing by one blade 286 from one lower section toanother. In other embodiments, the upper and lower sections may differin the number of blades 286 by approximately 1 to 1.005, 1 to 1.01, 1 to1.02, 1 to 1.05, or 1 to 3 within each individual rotor and/or from onerotor to another. In addition, the blades 286 may be evenly or unevenlyspaced within each section 288, 290, 292, 294, 296, and 298.

In each of these embodiments, the non-uniform blade spacing isconfigured to reduce the possibility of resonance due to periodicgeneration of wake and bow waves. Furthermore, the non-uniform bladespacing may effectively dampen and reduce the response of stationaryairfoils or structures by the rotating airfoils or structure's wake andbow waves due to their non-periodic generation by the blades 286. Inthis manner, the non-uniform blade spacing is able to lessen the impactof wake and bow waves on various downstream components, e.g., vanes,nozzles, stators, airfoils, etc. In the embodiment of FIG. 5, thenon-uniform blade spacing is provided both within each individual rotor280, 282, and 284, and also from one rotor to another (e.g., one stageto another). Thus, the non-uniformity from one rotor to another mayfurther reduce the possibility of resonance caused by periodicgeneration of wake and bow waves in a rotary machine.

FIG. 6 is a section of a front view of an embodiment of a rotor 310 withdifferently sized spacers 312 between bases 314 of blades 316. Inparticular, the differently sized spacers 312 enable implementation of avariety of non-uniform blade spacing configurations with equally sizedbases 314 and/or blades 316, thereby reducing manufacturing costs of theblades 316. Although any number and size of spacers 312 may be used toprovide the non-uniform blade spacing, the illustrated embodimentincludes three differently sized spacers 312 for purposes of discussion.The illustrated spacers 312 include a small spacer labeled as “S”, amedium spacer labeled as “M”, and a large spacer labeled as “L.” Thesize of the spacers 312 may vary in a circumferential direction, asindicated by dimension 318 for the small spacer, dimension 320 for themedium spacer, and dimension 322 for the large spacer. In certainembodiments, a plurality of spacers 312 may be disposed between adjacentbases 314, wherein the spacers 312 are either of equal or differentsizes. In other words, the differently sized spacers 312 may be either aone-piece construction or a multi-piece construction using a pluralityof smaller spacers to generate a greater spacing. In either embodiment,the dimensions 318, 320, and 322 may progressively increase by apercentage of approximately 1 to 1000 percent, 5 to 500 percent, or 10to 100 percent. In other embodiments, the rotor 310 may include more orfewer differently sized spacers 312, e.g., 2 to 100, 2 to 50, 2 to 25,or 2 to 10. The differently sized spacers 312 (e.g., S, M, and L) alsomay be arranged in a variety of repeating patterns, or they may bearranged in a random order.

FIG. 7 is a top view of an embodiment of a rotor 322 with differentlysized spacers 324 between bases 326 of blades 328. Similar to theembodiment of FIG. 6, the differently sized spacers 324 enableimplementation of a variety of non-uniform blade spacing configurationswith equally sized bases 326 and/or blades 328, thereby reducingmanufacturing costs of the blades 328. Although any number and size ofspacers 324 may be used to provide the non-uniform blade spacing, theillustrated embodiment includes three differently sized spacers 324 forpurposes of discussion. The illustrated spacers 324 include a smallspacer labeled as “S”, a medium spacer labeled as “M”, and a largespacer labeled as “L.” The size of the spacers 324 may vary in acircumferential direction, as discussed above with reference to FIG. 5.The differently sized spacers 324 (e.g., S, M, and L) also may bearranged in a variety of repeating patterns, or they may be arranged ina random order.

In the illustrated embodiment, the spacers 324 interface with the bases326 of the blades 328 at an angled interface 330. For example, theangled interface 330 is oriented at an angle 332 relative to arotational axis of the rotor 322, as indicated by line 334. The angle332 may range between approximately 0 to 60 degrees, 5 to 45 degrees, or10 to 30 degrees. The illustrated angled interface 330 is a straightedge or flat surface. However, other embodiments of the interface 330may have non-straight geometries.

FIG. 8 is a top view of an embodiment of a rotor 340 with differentlysized spacers 342 between bases 344 of blades 346. Similar to theembodiment of FIGS. 6 and 8, the differently sized spacers 342 enableimplementation of a variety of non-uniform blade spacing configurationswith equally sized bases 344 and/or blades 346, thereby reducingmanufacturing costs of the blades 346. Although any number and size ofspacers 342 may be used to provide the non-uniform blade spacing, theillustrated embodiment includes three differently sized spacers 342 forpurposes of discussion. The illustrated spacers 342 include a smallspacer labeled as “S”, a medium spacer labeled as “M”, and a largespacer labeled as “L.” The size of the spacers 342 may vary in acircumferential direction, as discussed above with reference to FIG. 6.The differently sized spacers 342 (e.g., S, M, and L) also may bearranged in a variety of repeating patterns, or they may be arranged ina random order.

In the illustrated embodiment, the spacers 342 interface with the bases344 of the blades 346 at a non-straight interface 350. For example, theinterface 350 may include a first curved portion 352 and a second curvedportion 354, which may be the same or different from one another.However, the interface 350 also may have other non-straight geometries,such as multiple straight segments of different angles, one or moreprotrusions, one or more recesses, or a combination thereof. Asillustrated, the first and second curved portions 352 and 354 curve inopposite directions from one another. However, the curved portions 352and 354 may define any other curved geometry.

FIG. 9 is a front view of an embodiment of a blade 360 having a T-shapedgeometry 361, which may be arranged in a non-uniform blade spacing inaccordance with the disclosed embodiments. The illustrated blade 360includes a base portion 362 and a blade portion 364, which may beintegral with one another (e.g., one-piece). The base portion 362includes a first flange 366, a second flange 368 offset from the firstflange 366, a neck 370 extending between the flanges 366 and 368, andopposite slots 372 and 374 disposed between the flanges 366 and 368.During assembly, the flanges 366 and 368 and slots 372 and 374 areconfigured to interlock with a circumferential rail structure about therotor. In other words, the flanges 366 and 368 and slots 372 and 374 areconfigured to slide circumferentially into place along the rotor,thereby securing the blade 360 in the axial and radial directions. Inthe embodiments of FIGS. 6-8, these blades 360 may be spaced apart inthe circumferential direction by a plurality of differently sizedspacers having a similar base portion, thereby providing a non-uniformblade spacing of the blades 360.

FIG. 10 is a section of a front view of an embodiment of a rotor 384with differently sized bases 386 of blades 388. In particular, thedifferently sized bases 386 enable implementation of a variety ofnon-uniform blade spacing configurations with or without spacers. Ifspacers are used with the differently sized bases 386, the spacers maybe equally sized or differently sized to provide more flexibility in thenon-uniform blade spacing. Although any number of differently sizedbases 386 may be used to provide the non-uniform blade spacing, theillustrated embodiment includes three differently sized bases 386 forpurposes of discussion. The illustrated bases 386 include a small baselabeled as “S”, a medium base labeled as “M”, and a large base labeledas “L.” The size of the bases 386 may vary in a circumferentialdirection, as indicated by dimension 390 for the small base, dimension392 for the medium base, and dimension 394 for the large base. Forexample, these dimensions 390, 392, and 394 may progressively increaseby a percentage of approximately 1 to 1000 percent, 5 to 500 percent, or10 to 100 percent. In other embodiments, the rotor 384 may include moreof fewer differently sized bases 386, e.g., 2 to 100, 2 to 50, 2 to 25,or 2 to 10. The differently sized bases 386 (e.g., S, M, and L) also maybe arranged in a variety of repeating patterns, or they may be arrangedin a random order.

FIG. 11 is a top view of an embodiment of a rotor 400 with differentlysized blade bases 402 supporting blades 404. Similar to the embodimentof FIG. 10, the differently sized bases 402 enable implementation of avariety of non-uniform blade spacing configurations with or withoutspacers. Although any number and size of bases 402 may be used toprovide the non-uniform blade spacing, the illustrated embodimentincludes three differently sized bases 402 for purposes of discussion.The illustrated bases 402 include a small base labeled as “S”, a mediumbase labeled as “M”, and a large base labeled as “L.” The size of thebases 402 may vary in a circumferential direction, as discussed abovewith reference to FIG. 10. The differently sized bases 402 (e.g., S, M,and L) also may be arranged in a variety of repeating patterns, or theymay be arranged in a random order.

In the illustrated embodiment, the bases 402 interface with one anotherat an angled interface 406. For example, the angled interface 406 isoriented at an angle 408 relative to a rotational axis of the rotor 400,as indicated by line 409. The angle 408 may range between approximately0 to 60 degrees, 5 to 45 degrees, or 10 to 30 degrees. The illustratedangled interface 406 is a straight edge or flat surface. However, otherembodiments of the interface 406 may have non-straight geometries.

FIG. 12 is a top view of an embodiment of a rotor 410 with differentlysized blade bases 412 supporting blades 414. Similar to the embodimentof FIGS. 10 and 12, the differently sized bases 412 enableimplementation of a variety of non-uniform blade spacing configurationswith or without spacers. Although any number and size of bases 412 maybe used to provide the non-uniform blade spacing, the illustratedembodiment includes three differently sized bases 412 for purposes ofdiscussion. The illustrated bases 412 include a small base labeled as“S”, a medium base labeled as “M”, and a large base labeled as “L.” Thesize of the bases 412 may vary in a circumferential direction, asdiscussed above with reference to FIG. 10. The differently sized bases412 (e.g., S, M, and L) also may be arranged in a variety of repeatingpatterns, or they may be arranged in a random order.

In the illustrated embodiment, the bases 412 interface with one anotherat a non-straight interface 416. For example, the interface 416 mayinclude a first curved portion 418 and a second curved portion 420,which may be the same or different from one another. However, theinterface 416 also may have other non-straight geometries, such asmultiple straight segments of different angles, one or more protrusions,one or more recesses, or a combination thereof. As illustrated, thefirst and second curved portions 418 and 420 curve in oppositedirections from one another. However, the curved portions 418 and 420may define any other curved geometry.

FIG. 13 is a section of a front view of an embodiment of a stator 440with differently sized spacers 442 between bases 444 of vanes 446. Inparticular, the differently sized spacers 442 enable implementation of avariety of non-uniform vane spacing configurations with equally sizedbases 444 and/or vanes 446, thereby reducing manufacturing costs of thevanes 446. Although any number and size of spacers 442 may be used toprovide the non-uniform vane spacing, the illustrated embodimentincludes three differently sized spacers 442 for purposes of discussion.The illustrated spacers 442 include a small spacer labeled as “S”, amedium spacer labeled as “M”, and a large spacer labeled as “L.” Thesize of the spacers 442 may vary in a circumferential direction, asindicated by dimension 448 for the small spacer, dimension 450 for themedium spacer, and dimension 452 for the large spacer. In certainembodiments, a plurality of spacers 442 may be disposed between adjacentbases 444, wherein the spacers 442 are either of equal or differentsizes. In other words, the differently sized spacers 442 may be either aone-piece construction or a multi-piece construction using a pluralityof smaller spacers to generate a greater spacing. In either embodiment,the dimensions 448, 450, and 452 may progressively increase by apercentage of approximately 1 to 1000 percent, 5 to 500 percent, or 10to 100 percent. In other embodiments, the stator 440 may include more orfewer differently sized spacers 442, e.g., 2 to 100, 2 to 50, 2 to 25,or 2 to 10. The differently sized spacers 442 (e.g., S, M, and L) alsomay be arranged in a variety of repeating patterns, or they may bearranged in a random order.

FIG. 14 is a section of a front view of an embodiment of a stator 460with differently sized bases 462 of vanes 464. In particular, thedifferently sized bases 462 enable implementation of a variety ofnon-uniform vane spacing configurations with or without spacers. Ifspacers are used with the differently sized bases 462, the spacers maybe equally sized or differently sized to provide more flexibility in thenon-uniform vane spacing. Although any number of differently sized bases462 may be used to provide the non-uniform vane spacing, the illustratedembodiment includes three differently sized bases 462 for purposes ofdiscussion. The illustrated bases 462 include a small base labeled as“S”, a medium base labeled as “M”, and a large base labeled as “L.” Thesize of the bases 462 may vary in a circumferential direction, asindicated by dimension 466 for the small base, dimension 468 for themedium base, and dimension 470 for the large base. For example, thesedimensions 466, 468, and 470 may progressively increase by a percentageof approximately 1 to 1000 percent, 5 to 500 percent, or 10 to 100percent. In other embodiments, the stator 460 may include more of fewerdifferently sized bases 462, e.g., 2 to 100, 2 to 50, 2 to 25, or 2 to10. The differently sized bases 462 (e.g., S, M, and L) also may bearranged in a variety of repeating patterns, or they may be arranged ina random order.

As discussed above, the present embodiments may tune the fluid dynamicsin a rotary machine, such as a compressor or turbine, via an adjustmentof the spacing between rotating blades or stationary vanes and/or anadjustment of the count of rotating blades or stationary vanes. Thistuning may substantially reduce or eliminate the possibility ofresonance behavior in the rotary machine, e.g., resonant behavior due towakes and bow waves. The embodiments of FIGS. 2-14 provide a non-uniformspacing of rotating blades or stationary vanes, which may alsocorrespond with a change or no change in the count of the blades orvanes. The embodiments of FIGS. 15-21 specifically modify the count ofthe blades or vanes, while maintaining a uniform spacing of the bladesor vanes. As discussed in further detail below, changing the number ofblades or vanes on respective rotors and stators while maintaininguniform spacing changes the frequency of wake and bow waves at specificrotational speeds. For instance, altering the size of the spacers mayincrease or decrease the blade count by any suitable number, e.g., 1 to5, 1 to 10, or 1 to 20. This frequency change may prevent a long-lastingresonant response in structures along the flow path (e.g., rotors,stators, etc.) at specific rotational speeds.

FIGS. 15, 16, and 17 illustrate the use of three differently sizedspacers to provide a different uniform blade spacing and blade count,which may be selectively used to vary the frequency of wakes and bowwaves in a rotary machine such as a turbine or a compressor. AlthoughFIGS. 15, 16, and 17 illustrate only three sizes of spacers (i.e.,large, medium, and small), certain embodiments may employ any number ofspacer sizes (e.g., 2 to 100 different sizes) to modify the bladespacing and count. FIG. 15 is a section of a front view of an embodimentof a rotor 480 with large spacers 482 between blade bases 484 supportingblades 486. In the illustrated embodiment, the large spacers 482 have anequal size to separate adjacent blade bases 484 by an equal distance 488around the rotor 480. The large spacers 482 also separate the blades 486by an equal distance 490 around the rotor 480. Relative to the small andmedium spacers as illustrated in FIGS. 16 and 17, the large spacers 482decrease the number of blades 486 on the rotor 480, thereby decreasingthe frequency of the bow and wake waves. The large spacers 482 may beused to shift the frequency of the bow and wake waves away from aresonant frequency, e.g., if the medium or small spacers result in afrequency too close to the resonant frequency.

FIG. 16 is a section of a front view of an embodiment of a rotor 500with medium spacers 502 between blade bases 504 supporting blades 506.In the illustrated embodiment, the medium spacers 502 have an equal sizeto separate adjacent blade bases 504 by an equal distance 508 around therotor 500. The medium spacers 502 also separate the blades 506 by anequal distance 510 around the rotor 500. Relative to the large spacersas illustrated in FIG. 15, the medium spacers 502 increase the number ofblades 506 on the rotor 500, thereby increasing the frequency of the bowand wake waves. Relative to the small spacers as illustrated in FIG. 17,the medium spacers 502 decrease the number of blades 506 on the rotor500, thereby decreasing the frequency of the bow and wake waves. Themedium spacers 502 may be used to shift the frequency of the bow andwake waves away from a resonant frequency, e.g., if the large or smallspacers result in a frequency too close to the resonant frequency.

FIG. 17 is a section of a front view of an embodiment of a rotor 520with small spacers 522 between blade bases 524 supporting blades 526. Inthe illustrated embodiment, the small spacers 522 have an equal size toseparate adjacent blade bases 524 by an equal distance 528 around therotor 520. The small spacers 522 also separate the blades 526 by anequal distance 530 around the rotor 520. Relative to the large andmedium spacers as illustrated in FIGS. 15 and 16, the small spacers 522increase the number of blades 526 on the rotor 520, thereby increasingthe frequency of the bow and wake waves. The small spacers 522 may beused to shift the frequency of the bow and wake waves away from aresonant frequency, e.g., if the large and medium spacers result in afrequency too close to the resonant frequency.

FIG. 18 is a graph 530 illustrating a fluid oscillation frequency orvibration frequency versus rotational speed of a rotary machine, such asa turbine or a compressor. As illustrated in FIG. 18, the x-axis 532represents the rotational speed of the rotary machine, while the y-axis534 represents the fluid oscillation frequency or vibration frequency ofa structure in the fluid flow. The dashed vertical line 536 represents anormal rotational speed of the rotary machine, e.g., a design speed of aturbine engine. A curve 538 represents a resonant frequency of astructure in the fluid flow. For example, the curve 538 may correspondto a resonant frequency of vibration of a stationary structure (e.g.,vane) upstream or downstream from a rotating blade that produces wakeand bow waves. Lines 540, 542, and 544 represent the frequency ofoscillations of the fluid flow (e.g., wake or bow waves) driven byrotation of the blades, wherein each line 540, 542, and 544 represents adifferent count of equally spaced blades. In particular, the line 540represents a large count of blades provided by a plurality of smallspacers as represented by “S,” the line 542 represents a medium count ofblades provided by a plurality of medium spacers as represented by “M,”and the line 544 represents a small count of blades provided by aplurality of large spacers as represented by “L.” Accordingly, the line540 may correspond to the embodiment of FIG. 17, the line 542 maycorrespond to the embodiment of FIG. 16, and the line 544 may correspondto the embodiment of FIG. 15.

As illustrated in FIG. 18, an increase in the blade count correspondingto a decrease in the spacer size causes an increase in the frequency ofoscillations (e.g., wake or bow waves) generated by the blades, whereasa decrease in the blade count corresponding to a increase in the spacersize causes an decrease in the frequency of oscillations (e.g., wake orbow waves) generated by the blades. Thus, the disclosed embodimentsadjust the spacer size to alter the blade count, and thus alter thefrequency of oscillations, to avoid the resonant frequency for aparticular rotational speed. The intersections of the lines 540, 542,and 544 with the line 538 represent resonant points 546, 548, and 550for the different blade counts. For example, the resonant point 546represents a first resonant frequency 552 at a first rotational speed554, wherein the frequency of oscillations (e.g., wake or bow waves)generated by rotation of the blades 526 of FIG. 17 (i.e., small spacers;large blade count) intersects with the resonant frequency of thestructure (e.g., vane) upstream or downstream from the blades 526. Byfurther example, the resonant point 548 represents a second resonantfrequency 556 at a second rotational speed 558, wherein the frequency ofoscillations (e.g., wake or bow waves) generated by rotation of theblades 506 of FIG. 16 (i.e., medium spacers; medium blade count)intersects with the resonant frequency of the structure (e.g., vane)upstream or downstream from the blades 506. By further example, theresonant point 550 represents a third resonant frequency 560 at a thirdrotational speed 562, wherein the frequency of oscillations (e.g., wakeor bow waves) generated by rotation of the blades 486 of FIG. 15 (i.e.,large spacers; small blade count) intersects with the resonant frequencyof the structure (e.g., vane) upstream or downstream from the blades486.

In the illustrated embodiment, the second rotational speed 558 isgenerally the same as the design rotational speed 536 of the rotarymachine, and thus the line 542 corresponding to the medium count ofblades (e.g., FIG. 16) would likely result in resonant behavior of thestructure (e.g., vane) upstream or downstream from the rotating blades506. Accordingly, the disclosed embodiments may employ either a greateror lesser count of blades to avoid this resonant behavior at the designrotational speed 536 of the rotary machine. For example, the disclosedembodiments may employ the greater count of blades provided by smallerspacers as depicted in FIG. 17, or the lesser count of blades providedby the larger spacers as depicted in FIG. 15. At the design rotationalspeed 536, the greater count of blades provided by smaller spacers asdepicted in FIG. 17 would result in a frequency 564 of oscillations(e.g., wakes or bow waves) substantially greater than the resonantfrequency 556, thereby substantially preventing any resonant behavior inthe structure (e.g., vane) upstream or downstream from the blades.Similarly, at the design rotational speed 536, the lesser count ofblades provided by larger spacers as depicted in FIG. 15 would result ina frequency 566 of oscillations (e.g., wakes or bow waves) substantiallylesser than the resonant frequency 556, thereby substantially preventingany resonant behavior in the structure (e.g., vane) upstream ordownstream from the blades. Although FIGS. 15-18 represent only threesizes of spacers (i.e., large 482, medium 502, and small 522), anynumber of differently sized spacers may be used to adjust the count ofblades with a uniform blade spacing, thereby avoiding any resonantbehavior in the rotary machine.

Similar to the modification of blade spacing of rotating blades asdiscussed above with reference to FIGS. 15-18, the disclosed embodimentsalso include modification of vane spacing of stationary vanes asdiscussed below with reference to FIGS. 19, 20, and 21. FIGS. 19, 20,and 21 illustrate the use of three differently sized spacers to providea different uniform vane spacing and vane count, which may beselectively used to vary the frequency of wakes and bow waves in arotary machine such as a turbine or a compressor. Although FIGS. 19, 20,and 21 illustrate only three sizes of spacers (i.e., large, medium, andsmall), certain embodiments may employ any number of spacer sizes (e.g.,2 to 100 different sizes) to modify the blade spacing and count. In eachembodiment, the spacers may be selected to alter the vane count tocontrol the frequency of oscillations (e.g., wakes or bow waves),thereby ensuring that the frequency of oscillations does not coincidewith a resonant frequency.

FIG. 19 is a section of a front view of an embodiment of a stator 570with large spacers 572 between vane bases 574 supporting vanes 576. Inthe illustrated embodiment, the large spacers 572 have an equal size toseparate adjacent vane bases 574 by an equal distance 578 around thestator 570. The large spacers 572 also separate the vanes 576 by anequal distance 580 around the stator 570. Relative to the small andmedium spacers as illustrated in FIGS. 20 and 21, the large spacers 572decrease the number of vanes 576 on the stator 570, thereby decreasingthe frequency of the bow and wake waves. The large spacers 572 may beused to shift the frequency of the bow and wake waves away from aresonant frequency, e.g., if the medium or small spacers result in afrequency too close to the resonant frequency.

FIG. 20 is a section of a front view of an embodiment of a stator 590with medium spacers 592 between vane bases 594 supporting vanes 596. Inthe illustrated embodiment, the medium spacers 592 have an equal size toseparate adjacent vane bases 594 by an equal distance 598 around thestator 590. The medium spacers 592 also separate the vanes 596 by anequal distance 600 around the stator 590. Relative to the large spacersas illustrated in FIG. 19, the medium spacers 592 increase the number ofvanes 596 on the stator 590, thereby increasing the frequency of the bowand wake waves. Relative to the small spacers as illustrated in FIG. 21,the medium spacers 592 decrease the number of vanes 596 on the stator590, thereby decreasing the frequency of the bow and wake waves. Themedium spacers 592 may be used to shift the frequency of the bow andwake waves away from a resonant frequency, e.g., if the large or smallspacers result in a frequency too close to the resonant frequency.

FIG. 21 is a section of a front view of an embodiment of a stator 610with small spacers 612 between vane bases 614 supporting vanes 616. Inthe illustrated embodiment, the small spacers 612 have an equal size toseparate adjacent vane bases 614 by an equal distance 618 around thestator 610. The small spacers 612 also separate the vanes 616 by anequal distance 620 around the stator 610. Relative to the large andmedium spacers as illustrated in FIGS. 19 and 20, the small spacers 612increase the number of vanes 616 on the stator 610, thereby increasingthe frequency of the bow and wake waves. The small spacers 612 may beused to shift the frequency of the bow and wake waves away from aresonant frequency, e.g., if the large and medium spacers result in afrequency too close to the resonant frequency.

The embodiments discussed above are directed to changing the frequencyof wake and bow waves generated by rotating blades or stationary vanes,such that the frequency does not intersect with a resonant frequency ofvarious structures in the fluid flow. As appreciated, the non-uniformspacing or modified count of rotating blades or stationary vanes may beapplied to a single stage of a rotary machine (e.g., a turbine or acompressor), or it may be applied to multiple stages in a similar ordifferent configuration. For example, each stage in a compressor orturbine may change the non-uniform spacing or modified count of bladesor vanes to address different fluid dynamics in each particular stage.In other words, each stage may exhibit different resonant behavior,frequencies of wake and bow waves, and other characteristics. Thus, thedisclosed embodiments may employ a combination of non-uniform spacingand a modified count of blades and vanes to address the different fluiddynamics from one stage to another.

Technical effects of the disclosed embodiments include the ability todampen fluid oscillations (e.g., wake or bow waves) and/or reduceresonant behavior caused by the fluid oscillations in a rotary machine.In particular, the disclosed embodiments adjust the spacing and/or countof blades or vanes to control the frequency of wake and bow waves formedby the rotating blades, stationary vanes, or other structures in thefluid flow. For example, a non-uniform spacing of rotating blades orstationary vanes may be achieved with differently sized spacers betweenadjacent blades or vanes, differently sized bases of the blades orvanes, or a combination thereof. By further example, a modified count ofrotating blades or vanes may be achieved with different sets of spacers,each configured to provide a different uniform spacing of the blades orvanes. The non-uniform spacing or modified count of blades or vanes isable to reduce the possibility of resonant behavior in the rotarymachine, thereby reducing the possibility of costly wear and damage ofvanes, blades, and other structures in the fluid flow path.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they have structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal language of the claims.

1. A system, comprising: a rotary machine comprising: a fluid flow pathextending along an axis of the rotary machine; a plurality of airfoilsdisposed about the axis; and a plurality of spacers disposed about theaxis, wherein each spacer of the plurality of spacers is disposedcircumferentially between adjacent airfoils of the plurality of airfoilsto define a circumferential spacing of the airfoils about the axis. 2.The system of claim 1, wherein the circumferential spacing of theplurality of airfoils is configured to reduce resonant behavior in therotary machine.
 3. The system of claim 1, wherein the rotary machinecomprises a turbine.
 4. The system of claim 1, wherein the rotarymachine comprises a compressor.
 5. The system of claim 1, wherein therotary machine comprises a stator and a rotor, the plurality of airfoilsare coupled to the rotor, and the plurality of spacers are coupled tothe rotor.
 6. The system of claim 1, wherein the rotary machinecomprises a stator and a rotor, the plurality of airfoils are coupled tothe stator, and the plurality of spacers are coupled to the stator. 7.The system of claim 1, wherein the plurality of spacers have an equalwidth in a circumferential direction about the axis.
 8. The system ofclaim 1, comprising a plurality of replacement spacers configured toreplace the plurality of spacers, wherein the plurality of replacementspacers have a different width than the plurality of spacers.
 9. Thesystem of claim 1, comprising a plurality of second airfoils and aplurality of second spacers disposed about the axis, wherein each secondspacer of the plurality of second spacers is disposed circumferentiallybetween adjacent second airfoils of the plurality of second airfoils todefine a second circumferential spacing of the second airfoils about theaxis.
 10. The system of claim 9, wherein the circumferential spacing ofthe plurality of airfoils is configured to reduce resonant behavior inthe rotary machine, and the second circumferential spacing of theplurality of second airfoils is configured to reduce resonant behaviorin the rotary machine.
 11. A system, comprising: a rotary machinecomprising: a fluid flow path; and a plurality of segments disposed inan annular arrangement along the fluid flow path, wherein the pluralityof segments comprise spacer segments and flow control segments, the flowcontrol segments protrude into the fluid flow path, and each spacersegment is disposed circumferentially between adjacent flow controlsegments to define a circumferential spacing of the flow controlsegments.
 12. The system of claim 11, wherein the circumferentialspacing of the flow control segments is configured to reduce resonantbehavior in the rotary machine.
 13. The system of claim 11, wherein therotary machine comprises a turbine, a compressor, or a combinationthereof.
 14. The system of claim 11, wherein the plurality of segmentsare stationary, and the flow control segments comprise stationary vanes.15. The system of claim 11, wherein the plurality of segments arerotatable, and the flow control segments comprise rotatable blades. 16.The system of claim 11, wherein the spacer segments have an equal widthin a circumferential direction about the annular arrangement.
 17. Thesystem of claim 11, comprising replacement spacer segments configured toreplace the spacer segments, wherein the replacement spacer segmentshave a different width than the spacer segments.
 18. A method,comprising: mounting a plurality of airfoil segments in a rotary machinealong a fluid flow path; and spacing the plurality of airfoil segmentsin a circumferential spacing with a plurality of spacer segments. 19.The method of claim 18, comprising reducing resonant behavior in therotary machine by adjusting a number of the plurality of airfoilsegments and by adjusting a width and number of the plurality of spacersegments.
 20. The method of claim 19, wherein mounting comprisingremovably attaching the plurality of airfoil segments and the pluralityof spacer segments in a turbine, a compressor, or a combination thereof.